U.S. patent application number 11/564891 was filed with the patent office on 2007-05-31 for device for exhaust gas purification for spark-ignited engines.
Invention is credited to Janusz POPIK, Ryszard Zbigniew Popik, Justin Xiaogang Yao.
Application Number | 20070119433 11/564891 |
Document ID | / |
Family ID | 38121230 |
Filed Date | 2007-05-31 |
United States Patent
Application |
20070119433 |
Kind Code |
A1 |
POPIK; Janusz ; et
al. |
May 31, 2007 |
DEVICE FOR EXHAUST GAS PURIFICATION FOR SPARK-IGNITED ENGINES
Abstract
The exhaust gas purification device has a first chamber having
an exhaust pipe inlet, an ambient air inlet, and an exhaust gas
outlet. A Venturi is arranged within the chamber, having an inlet
end communicating with an ambient air inlet, a throat, and an
outlet end communicating with an exhaust gas outlet. The Venturi
has an exhaust gas inlet between its inlet end and its outlet end,
receiving exhaust gas from within the chamber, directed generally
towards the outlet end of the Venturi, so that ambient air and
exhaust air are mixed in passing through the Venturi to its exhaust
gas outlet. A perforated pipe within the first chamber receives the
exhaust gas, and the exhaust gas escapes therefrom via the
perforations, into the chamber and thence to the Venturi. A second
chamber, having a catalytic substrate assembly mounted therein,
receives the mixed ambient air and exhaust air from the exhaust gas
outlet of the Venturi, and has an exhaust pipe outlet.
Inventors: |
POPIK; Janusz; (Mississauga,
CA) ; Popik; Ryszard Zbigniew; (Brampton, CA)
; Yao; Justin Xiaogang; (Markham, CA) |
Correspondence
Address: |
BORDEN LADNER GERVAIS LLP
WORLD EXCHANGE PLAZA
100 QUEEN STREET SUITE 1100
OTTAWA
ON
K1P 1J9
CA
|
Family ID: |
38121230 |
Appl. No.: |
11/564891 |
Filed: |
November 30, 2006 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
60740667 |
Nov 30, 2005 |
|
|
|
Current U.S.
Class: |
123/568.17 |
Current CPC
Class: |
F01N 2470/30 20130101;
F01N 1/02 20130101; F01N 3/05 20130101; Y02T 10/12 20130101; F01N
3/2885 20130101; F01N 2470/16 20130101 |
Class at
Publication: |
123/568.17 |
International
Class: |
F02M 25/07 20060101
F02M025/07; F02B 47/08 20060101 F02B047/08 |
Claims
1. An exhaust gas purification device for a spark-ignited engine,
comprising a Venturi having an inlet end receiving ambient air, a
throat, and an outlet end, said Venturi having an exhaust gas inlet
between its inlet end and its outlet end receiving exhaust gas
directed generally towards said outlet end, said exhaust gas
thereby drawing ambient air through said inlet, and exhaust gas and
ambient air thereby being mixed en route to said outlet end.
2. An exhaust gas purification device as in claim 1, wherein said
outlet end communicates with an exhaust outlet pipe, with a
catalytic substrate assembly interposed therebetween.
3. An exhaust gas purification device as in claim 1, wherein said
exhaust gas inlet is between said inlet end and said throat.
4. An exhaust gas purification device as in claim 3, wherein an
ambient air inlet element extends towards said inlet end of said
Venturi, with said exhaust gas entering said Venturi radially
outward from said ambient air inlet element.
5. An exhaust gas purification device for a spark-ignited engine,
comprising: a first chamber having an exhaust pipe inlet, an
ambient air inlet, and an exhaust gas outlet; and a Venturi
arranged within said first chamber, having an inlet end
communicating with said ambient air inlet, a throat, and an outlet
end communicating with said exhaust gas outlet, said Venturi having
an exhaust gas inlet between its inlet end and its outlet end
receiving said exhaust gas from within said chamber, directed
generally towards said outlet end; whereby ambient air and exhaust
air are mixed in passing through said Venturi to its exhaust gas
outlet.
6. An exhaust gas purification device as in claim 5, further
comprising a second chamber adjacent said first chamber, said
second chamber having a catalytic substrate assembly mounted
therein, receiving mixed ambient air and exhaust air from said
exhaust gas outlet of said Venturi, said second chamber further
having an exhaust pipe outlet.
7. An exhaust gas purification device as in claim 5, further
comprising a first passage within said first chamber, communicating
with said exhaust pipe inlet, and having a plurality of openings
for exhaust gas to exit therefrom into the rest of said first
chamber and thence to said Venturi.
Description
REFERENCE TO RELATED APPLICATION
[0001] This is a formal application based on and claiming the
benefit of provisional patent application No. 60/740,667, filed
Nov. 30, 2005.
BACKGROUND OF THE INVENTION
[0002] This invention relates generally to spark-ignited engines.
More particularly, this invention relates to a device for exhaust
gas purification for spark-ignited engines.
[0003] Exhaust emissions from spark-ignited engines, especially
from small spark-ignited engines such as those used in lawn mowers,
small generators, floor cleaning machines, are significant sources
of harmful pollution gases. In contrast to automotive engines which
are equipped with a closed-loop air/fuel ratio control system, such
engines operate without an air/fuel ratio control system in a
fuel-rich environment, and are much dirtier than automotive
engines. In order to reduce harmful exhaust emissions, a three-way
catalytic (TWC) converter is widely used. With fuel-rich
combustion, the TWC converter cannot reduce carbon monoxide (CO),
hydrocarbon (HC) and nitrogen oxides (NO.sub.x) simultaneously at
its maximum efficiencies due to a lack of the oxygen which is
needed for full catalyst functionality. Hence, it is desirable to
introduce a certain amount of secondary air into the exhaust stream
ahead of the TWC catalyst/converter to compensate for the oxygen
shortage in the engine-out emissions
[0004] There have been some exhaust emission purification devices
using Venturi devices to help introduce secondary air into raw
exhaust and enhance TWC catalyst efficiency. These Venturis use a
traditional type of structure including a tubing or narrow channel
with a convergent contraction structure (a throat) in the middle,
and a small passage or multi-holes/apertures connecting the Venturi
throat to the ambient in order to draw in secondary air. The
exhaust flow stream goes into and exits the Venturi in line. The
secondary air is introduced usually perpendicularly to the main
flow stream of the exhaust. Due to exhaust pressure pulsation,
there is often a back-flow or blow-out problem, i.e. the untreated
harmful exhaust gases are blown out through the secondary air
passage prior to entering the TWC catalyst whenever the exhaust
pressure is higher than the ambient pressure. Another challenge is
to compromise pressure drop and vacuum level for best
performance.
[0005] In general, therefore, the performance of prior art devices
has been lacking, and there is a need for an alternative device to
provide suitable exhaust gas purification for spark-ignited
engines.
SUMMARY OF THE INVENTION
[0006] It is an object of the invention to provide an exhaust gas
purification device which avoids or mitigates some of the problems
of prior art devices and/or which improves on prior art
devices.
[0007] The following summary refers to some specific features and
advantages which are not necessarily present in all embodiments of
the invention. The invention is as defined by the claims, not by
this summary.
[0008] In an exemplary embodiment, the invention includes a
three-way catalytic (TWC) converter or TWC muffler together with a
built-in Venturi for spark-ignited internal combustion engine and
open-loop fuel supply system. The Venturi device includes an
anti-backflow feature and strong vacuum-creating ability over a
traditional Venturi device. The device has no moving parts and is
relatively inexpensive to manufacture.
[0009] The Venturi device may be incorporated in an engine exhaust
system for the purpose of lowering exhaust temperature or diluting
the exhaust to lower emissions level in applications involving
confined working areas such as warehouses, underground mines, or
other areas where there are needs to lower the exhaust temperature
and exhaust dilution.
[0010] The device may include a metal housing with exhaust inlet
pipe and outlet pipe, made of any metal alloy but preferably of
stainless steel, mild steel or aluminized steel sheet. In various
embodiments, the following may be housed within the housing: a
Venturi structure with means of connecting to both the engine
exhaust and ambient, stamped members which are plates or disks that
divide the internal housing into at least two chambers with tubes
connecting the chambers if necessary, a TWC catalytic substrate
located downstream of the Venturi structure, and a means (said
outlet pipe) for outputting the exhaust gases after they have been
treated in the TWC catalyst.
[0011] The Venturi may include structure that allows the exhaust
stream to flow sideways to the cylindrical Venturi structure and
turn around to pass through the narrow throat to the Venturi
outlet. The ambient air (secondary air) is sucked in due to the
vacuum created by the higher gas speed at the location of the
throat and joins the exhaust flow in the same direction. In
traditional Venturis, the main exhaust gases flow in and out of the
Venturi in the same direction while secondary air flows sideways,
joining the main exhaust stream.
[0012] If desired, a one-way valve may be provided in the ambient
air inlet in order to avoid any untreated exhaust gases being blown
out when strong exhaust pulsation exists. The Venturi structure
size can be altered according to exhaust flow range and back
pressure range.
[0013] The TWC catalytic substrate can be any of flow-though
ceramic monolith with different cell densities or a metallic
substrate or a wire mesh or ceramic/metallic foam or any of their
combination coated with catalytic washcoat and catalyst materials
such as platinum, rhodium, palladium or any of their combinations,
or any other suitable substrate presently known or developed in
future.
[0014] The preferred embodiment of the invention may have some or
all of the following advantages: reduced risk of exhaust back-flow
or blow-out through the Venturi secondary air passage, due to the
unique Venturi structure making use of the flow kinetic energy and
creating a rectifying effect against possible back-flow; a pressure
drop over the Venturi structure which may be lower than that of
most conventional Venturis; greater capability in terms of
introducing secondary air than with a conventional Venturi,
resulting in a smaller Venturi size and therefore reducing the cost
of the device; eliminating a significant percentage of the harmful
exhaust emissions such as carbon monoxide (CO), hydrocarbon (HC)
and nitrogen oxides (NO.sub.x) coming from the combustion of a
spark-ignited internal combustion engine especially without
stoichiometric air/fuel ratio control system; and providing cooler
exhaust temperature or exhaust dilution in applications where that
is required or desired.
[0015] Other aspects and features of the present invention will
become apparent to those ordinarily skilled in the art upon review
of the following description of specific embodiments of the
invention in conjunction with the accompanying drawings.
BRIEF DESCRIPTION OF THE DRAWINGS
[0016] Embodiments of the present invention will now be described,
by way of example only, with reference to the accompanying
drawings, wherein:
[0017] FIG. 1 is a cross-sectional side view of a preferred
embodiment of a device according to the invention;
[0018] FIG. 2 is a cross-sectional side view of the Venturi
structure within the device; and
[0019] FIG. 3 is a perspective view of the preferred embodiment,
with the outer housing partially cut away for clarity.
DETAILED DESCRIPTION
[0020] FIG. 1 is a side view of an exemplary embodiment of the
exhaust gas purification device, and FIG. 3 is a cut-away
perspective view. In this example, the device is attached to the
exhaust manifold of a small spark-ignited ("S.I.") gasoline engine,
such as a Honda GCV160 (not shown). The device is affixed to the
engine exhaust manifold by through-bolts 14 so as to receive the
untreated raw exhaust gases 50 from the engine. It is to be
understood that although the example of this embodiment uses
through-bolts the attachment methods of the device to an engine
exhaust system could be any method such as flanged attachment,
welding, etc.
[0021] As illustrated in FIGS. 1 and 3, the device has an outer
housing 3. Across the front of the outer housing is a stamped front
cap 1 with an open ambient air inlet element, here in the form of a
cone 5, to a Venturi 9 and an exhaust gas inlet opening which
accommodates a perforated exhaust gas inlet pipe 2. At the rear of
the outer housing is a stamped rear cap 15. An exhaust outlet pipe
16 extends out the side of the housing near the rear thereof.
[0022] Inside the device, there are two expansion chambers
separated by a stamped separation plate 12. The first chamber 4
holds the Venturi 9 while the second chamber 13 accommodates the
catalytic substrate assembly 11. It is to be understood that any of
the chambers could function either as resonator together with
perforated tubing or as expansion chamber for noise attenuation
purposes, for the purification device to act as an exhaust
catalytic muffler, and if desired, there could be more than two
expansion chambers. The perforated exhaust inlet pipe 2 in this
embodiment is welded to the stamped front cap 1 and to the
separation plate 12.
[0023] As seen more clearly in FIG. 2, the Venturi 9 has an air
injector 6, the main Venturi body 8 (a convergent part, a throat
and a divergent part), and the outer shell 9a. The air injector 6
could be constructed together with a perforated cap that has
potentially adjustable openings or holes in order to adjust or
control the secondary air quantity and create a suitable exhaust
mixture for optimal catalyst activity. A one-way valve could be
added in front of the air injector, with or without the perforated
cap, to avoid exhaust backflow into the ambient air through the air
injector 6 in case the exhaust pulsation is very strong.
[0024] The catalyst substrate 11 is preferably made of but not
limited to ceramic and metallic cores with cell densities from 300
to 900 cpsi (cells per square inch) and ceramic and metallic foams
with pore densities from 20-50 ppi (pores per inch). The substrate
cross-section may take shapes of round, race-track, oval,
rectangle, square or other irregular shapes if needed. The
catalysts used for this invention could be based on single metal
(Pt-platinum, Pd-palladium), bi-metal (Pt/Rh-rhodium or Pd/Rh) or
tri-metal (Pt/Pd/Rh) catalyst formulations with metal loading
ranges preferably from 0.2% to 1.5%. The catalyst washcoat
materials could be Alumina, Zirconia or their combination mixed
with different precursors, promoters and stabilizers such as but
not limited to any salts and oxides of rare earth materials (Ba,
Ce, La, etc). The catalyst substrate is not the point of the
invention, and could vary according to the prior art and future
developments.
[0025] In operation, S.I. internal combustion engines without
electronic air/fuel ratio control usually work at rich air/fuel
mixture which gives rise to raw exhaust gases that lack enough
oxygen for effective catalytic conversion. The untreated raw
exhaust gases 50 shown in FIG. 1 flow into the purification device
through perforated inlet pipe 2. The exhaust flow 51 then goes
through the perforated holes and expands in the chamber 4 which
results in noise attenuation and damps the exhaust pressure
pulsation. It is important for the pressure damping to occur before
exhaust gases enter the Venturi because the pressure pulsation
could cause untreated exhaust blow-out through Venturi air injector
6 to ambient, unless there is a one-way valve (described above as
an option).
[0026] The exhaust flow 51 then moves into the Venturi through the
opening as shown in FIG. 1 and FIG. 2, and finds its way through
the gap 7 towards the Venturi throat 8a (FIG. 2). When the flow 51
passes through the narrow gap at high speed, a vacuum is created
both at the gap and at the Venturi throat which draws fresh air 53
from ambient air through inlet cone 5 and air injector 6. The fresh
air is then mixed with the raw exhaust 51 and the new mixture 52
leaves the Venturi through divergent section 8b (FIG. 2) and
connecting cone 10, producing a suitable exhaust mixture 54 with
enough oxygen before entering the catalytic substrate 11. One
important feature in this invention is that the ambient air joins
the main exhaust flow in the same direction instead of entering
sideways as in a traditional Venturi design. The kinetic energy of
the ambient stream greatly reduces the possibility of partial
exhaust flow back to the ambient through Venturi inlet due to
exhaust pressure pulsation.
[0027] After mixing of the raw exhaust 51 with fresh air 53 in the
Venturi, the new exhaust mixture 52 is ready to go through the TWC
catalyst for purification. With enough oxygen in the exhaust
mixture, the catalyst 11 is now able to convert the three emission
gases simultaneously, i.e. from CO, HC and NO.sub.xto C0.sub.2,
H.sub.2O and N.sub.2. The treated gases 55 then go into second
expansion chamber 13 for further noise attenuation and leave the
purification device as purified gases 56 through exhaust outlet
16.
[0028] The above-described embodiments of the present invention are
intended to be examples only. Alterations, modifications and
variations may be effected to the particular embodiments by those
of skill in the art without departing from the scope of the
invention, which is defined solely by the claims appended
hereto.
* * * * *